The present invention relates to an internal combustion engine which has a cooling circuit and a heating heat exchanger connected to it.
The German patent document DE 196 39 146 discloses an internal combustion engine with an exhaust gas line in which an exhaust gas catalyst is arranged, with an exhaust gas turbo-charger whose exhaust gas turbine is located upstream of the exhaust gas catalyst in the exhaust gas line, with a bypass conduit which on the one hand opens upstream of the exhaust gas turbine and on the other hand opens between the exhaust gas turbine and the exhaust gas line, with a controllable bypass valve in a bypass conduit, and with means for controlling the bypass valve. The bypass control means for the bypass valve after the start of the internal combustion engine and during a catalyst heating time period is partially open by a motor load below a predetermined motor load threshold value, and is held closed with the motor load above the motor load threshold value. This at least partial opening of the bypass valve after the start of the motor and thereby in idle running or at low motor load has the advantage of an accelerated heating of the catalyst, so that it takes earlier its associated objective of catalytic action than after the start of the internal combustion engine when all exhaust gas exiting the same flows to a turbine housing and turbine wheel of the exhaust gas turbocharger. For providing such at least partial opening of the bypass valve during idle running of the internal combustion engine, a so-called bi-pressure box is utilized as a control means for the bypass valve. It is subdivided by a diaphragm piston into two pressure chambers. One pressure chamber is controlled with the use of an electrically controllable 3/2 displacement valve by a control device operating with pulse width modulation, and adjusts a pressure between a synthetic pressure and a bearing pressure in the pressure chamber producible by the exhaust gas turbocharger. The other pressure chamber provides by a further electrically controllable 3/2 displacement valve a pressure between the atmospheric pressure and occasional subatmospheric pressure within a suction conduit of the internal combustion engine. The above mentioned patent mentions that alternatively to the bi-pressure box and thereby also to the both associated 3/2 displacement valves on the other hand, conventional adjustments for the bypass valve can be used as well.
Such adjustment means are disclosed for example in the European patent document EP 0 607 523. This adjustment means combine from the mono-pressure box, only an electronically controllable 3/2 displacement valve, and an air pump which supplies the 3/2 displacement valve at least at the inlet side when the exhaust gas turbocharger does not produce any low pressure or must produce. Instead of the both means for controlling the bypass valve which derive there adjusting force from air pressure differences, alternatingly also combinations of electric motors and mechanical transmissions driven by them are possible.
It is known in ATZ Automobiltechnische Zeitschrift 100 (1998) 7/8, Friedrich Vieweg and Sohn Verlagsgesellschaft mbH in the GWV Verlagsgesellschaft mbH, Posffach 15 46, D-65005 Wiesbaden, pages 486 through 488, that additionally to this heat from a cooling fluid of an internal combustion engine, also use of waste heat for a consumer-neutral heating power increases a vehicle passenger salon heating. For this purpose downstream of a catalyst which is provided on the internal combustion engine, a so-called exhaust gas deflector is provided which has a first outlet and a second outlet. The first outlet opens into a bypass conduit and the second outlet opens into an exhaust gas heat exchanger which in turn opens to a noise damper. Depending on the position of the exhaust gas deflector, exhaust gas flows to the bypass and also past the exhaust gas heat exchanger or the exhaust gas is supplied by adjusting the exhaust gas deflector through the exhaust gas heat exchanger so that the exhaust gas heat exchanger can withdraw heat from the exhaust gas.
This heat is supplied to a heating heat exchanger by a circulation circuit. Through a further connection also cooling fluid which is heated by the internal combustion engine is supplied to the heating heat exchanger, so that the heating heat exchanger belongs to two liquid circuits and therefore has a complicated construction. Another disadvantage is the technical expenses for the exhaust gas deflector. Since these exhaust gas deflectors contain a controllable flap which does not exclude a leakage flow, an additional heat exchanger is introduced into the circulation circuit for the purpose of avoiding, for example in summer, an undesired heating or even overheating of the exhaust gas heat exchanger by withdrawal of heat to the cooling circuit of the internal combustion engine. Naturally, an additional heat exchanger and a cooler of the cooling circuit adapted to it, increase technical expenses and therefore the price of a vehicle.
Accordingly, it is an object of the present invention to provide an internal combustion engine with a cooling circuit and a heating heat exchanger connected to it, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in an internal combustion engine which has an exhaust gas line; an exhaust gas heat exchanger through which exhaust gas withdrawn through said exhaust gas line passes so as to withdrew heat energy; a heating heat exchanger to which the withdrawn heat energy is made available and which is connected to a cooling fluid circuit of the internal combustion engine; an exhaust gas turbocharger provided with a turbine housing and a turbine wheel rotatable in the latter, said exhaust gas turbocharger being arranged in said exhaust gas line, said exhaust gas heat exchanger being connected heat-conductively with said turbine housing of said exhaust gas turbocharger for withdrawing of heat from the exhaust gas which passes through said turbine wheel.
When the internal combustion engine with an exhaust gas turbocharger is designed in accordance with the present invention, heat of the exhaust gas of the internal combustion engine in the immediate vicinity to the latter is taken through the wall of a turbine housing of the turbocharger for heating purposes. This makes possible, to supply the heating heat exchanger with an additional heat through a short additional cooling medium conduit portion and thereby to avoid the expenses for an exhaust gas deflector described in the above mentioned publication and therefore a complicated construction of the exhaust gas device.
In accordance with another feature of the present invention, the internal combustion engine has said turbine housing formed at least partially with an additional wall to form a hollow chamber provided with an inlet connection and an outlet connection for supplying and withdrawing of heat receiving cooling fluid upstream of said heating heat exchanger. This provides for a one-piece construction of the turbine housing of the exhaust gas turbocharger with the exhaust gas heat exchanger. Since for navigation the exhaust gas turbocharger with a liquid cooling of the turbine housing is acceptable, with this construction corresponding know-how can be taken as well.
In accordance with a further feature of the present invention, the internal combustion engine has a heating line leading to said heating heat exchanger, a directional valve arranged in said heating line, and a supply line leading from said directional valve to said exhaust gas heat exchanger, and directional valve is controllable so that cooling fluid which comes through said heating line is controllably distributed to said heating heat exchanger and/or said exhaust gas heat exchanger.
The advantage of this construction is that the exhaust heat exchanger operates by passing the cooling fluid selectively, for example to supply heat in winter to the heating heat exchanger and in summer, when only a little heating heat is needed, it is not filled, or in summer, and in the event of high thermal loads of the exhaust gas line it is used so as to cool the turbine housing and thereby the exhaust gas turbocharger and the exhaust gas.
In accordance with still a further feature of the present invention said directional valve is electrically controllable. This construction makes possible the passage of a cooling fluid through the exhaust gas heat exchanger for controlling by electrical control current, which are provided by a control device made in the internal combustion engine in dependence on preselected parameters. One of these parameters is for example the corresponding position of a heating adjustment lever or the like. For example, a simple flow of the exhaust gas heat exchanger can be suppressed when a fast heating of the catalyst is desired. Then, when cooling medium does not flow through the exhaust gas heat exchanger, the corresponding partial flow of exhaust gas which flows with the open bypass valve directly through the turbine wheel is cooled less.
In accordance with still a further feature of the present invention said directional valve is a three-two directional valve. With this construction a valve arrangement is provided which can be produced in a price-favorable manner.
Finally, in accordance with another advantageous feature of the present invention a check valve is located between said outlet connection of said exhaust gas heat exchanger and an inlet side of said heating heat exchanger, and the check valve is openable toward said heat exchanger. In this construction a pressure limiting valve for avoiding undesirable pressure increase in the exhaust gas heat exchanger is provided with the use of the 3/2 displacement valve with the advantage that the hollow chamber of the exhaust gas heat exchanger is for example emptied by evaporation of the cooling fluid. Therefore the temperature of the exhaust gas turbocharger can be increased over an evaporation temperature associated with the vapor pressure of the cooling circuit. Such a temperature increase can be desired for an efficient operation of the catalyst arranged after it.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.